<!DOCTYPE HTML>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>名师考题库首页</title>
    <link rel="stylesheet" type="text/css" href="../static/layui/css/layui.css"  />
    <script src="../static/js/zoneCommonJs/bgStar.css"></script>
    <script src="../static/js/zoneCommonJs/jquery.min.js"></script>

</head>
<style>
    .title {
        text-decoration:none;
        width: 100%;
        height: 43px;
        display: block;
        text-align:center;		/*水平居中*/
        line-height:43px;  /*上下居中*/
        cursor:pointer;
        position: absolute;
        top: 20%;
        float:left;/*左浮动*/
        margin:8px 2px 8px 2px;
        font:50px '华文新魏'; color:#066197;
        -webkit-animation: scaleDraw 10s ease-in-out infinite;
    }
    @keyframes scaleDraw {  /*定义关键帧、scaleDrew是需要绑定到选择器的关键帧名称*/
        0%{
            transform: translateX(0);  /*开始为原始大小*/
        }
        25%{
            transform: translateY(-50%);  /*开始为原始大小*/
        }
        50%{
            transform: translateX(0%);  /*开始为原始大小*/
        }
        75%{
            transform: translateY(50%);  /*开始为原始大小*/
        }
        100%{
            transform: translateX(0);
        }
    }
</style>
<body style="overflow: hidden">


<!-----HEADER STAR----->


<div class="header" id="demo">
    <span class="title">欢迎使用管理后台</span>
    <div class="canvaszz"> </div>
    <canvas id="canvas"></canvas>
</div>


<!-----HEADER END----->

<script>
    //宇宙特效
    "use strict";
    var canvas = document.getElementById('canvas'),
        ctx = canvas.getContext('2d'),
        w = canvas.width = window.innerWidth,
        h = canvas.height = window.innerHeight,

        hue = 217,
        stars = [],
        count = 0,
        maxStars = 200;//星星数量

    var canvas2 = document.createElement('canvas'),
        ctx2 = canvas2.getContext('2d');
    canvas2.width = 100;
    canvas2.height = 100;
    var half = canvas2.width / 2,
        gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
    gradient2.addColorStop(0.025, '#CCC');
    gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
    gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
    gradient2.addColorStop(1, 'transparent');

    ctx2.fillStyle = gradient2;
    ctx2.beginPath();
    ctx2.arc(half, half, half, 0, Math.PI * 2);
    ctx2.fill();

    // End cache

    function random(min, max) {
        if (arguments.length < 2) {
            max = min;
            min = 0;
        }

        if (min > max) {
            var hold = max;
            max = min;
            min = hold;
        }

        return Math.floor(Math.random() * (max - min + 1)) + min;
    }

    function maxOrbit(x, y) {
        var max = Math.max(x, y),
            diameter = Math.round(Math.sqrt(max * max + max * max));
        return diameter / 2;
        //星星移动范围，值越大范围越小，
    }

    var Star = function() {

        this.orbitRadius = random(maxOrbit(w, h));
        this.radius = random(60, this.orbitRadius) / 8;
        //星星大小
        this.orbitX = w / 2;
        this.orbitY = h / 2;
        this.timePassed = random(0, maxStars);
        this.speed = random(this.orbitRadius) / 50000;
        //星星移动速度
        this.alpha = random(2, 10) / 10;

        count++;
        stars[count] = this;
    }

    Star.prototype.draw = function() {
        var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
            y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
            twinkle = random(10);

        if (twinkle === 1 && this.alpha > 0) {
            this.alpha -= 0.05;
        } else if (twinkle === 2 && this.alpha < 1) {
            this.alpha += 0.05;
        }

        ctx.globalAlpha = this.alpha;
        ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);
        this.timePassed += this.speed;
    }

    for (var i = 0; i < maxStars; i++) {
        new Star();
    }

    function animation() {
        ctx.globalCompositeOperation = 'source-over';
        ctx.globalAlpha = 0.5; //尾巴
        ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)';
        ctx.fillRect(0, 0, w, h)

        ctx.globalCompositeOperation = 'lighter';
        for (var i = 1, l = stars.length; i < l; i++) {
            stars[i].draw();
        };

        window.requestAnimationFrame(animation);
    }

    animation();
</script>

</body>
</html>